While the case is not thought to have immediate implications for human health, it could provide a clue to the mechanism or transmission of the disease.
In neither victim was the illness caused by "mad cow disease", or BSE, said the doctors who report the incident today in the medical journal The Lancet. Yet the "strain" of CJD was the same in both.
CJD is a fatal human brain disease, part of a family of illnesses called transmissible spongiform encephalopathies (TSEs) which includes BSE in cows and scrapie in sheep. It is thought to be caused by a "rogue" protein whose accumulation leaves spongy holes in the brain before death.
So far, 27 Britons have died from a form of CJD caused by BSE-infected food, and since 1989 about 80 cats have died of "FSE", the feline version caused by infected cat food.
But humans also get "sporadic" CJD, which has no known cause, and affects about one person in a million each year. Typically this happens in people aged over 60.
In the Italian case, the man was admitted to hospital in November 1993, and died in January the following year. His cat started showing symptoms at about the same time and was put down. Tests showed that it had a "sporadic" form of the disease similar to the man's.
Dr Salvatore Monaco, who led the team of scientific investigators at the University of Verona, said the man had "no unusual dietary habits".
"It is unknown whether these TSEs occurred as a result of horizontal transmission [cross-infection] in either direction, infection from an unknown common source, or the chance occurrence of two sporadic forms," Dr Monaco said.Reuse content